1. Field of the Invention
The present invention relates to a lens controller, and particularly to a lens controller having an auto focus (AF) function.
2. Description of the Related Art
There is known a television camera, video camera, or the like having an auto focus (AF) function which automatically controls a focus so that a subject is in focus. A method of AF employed in a television camera or video camera is typically a method referred to as a contrast method, which detects a contrast of a subject image based on a picture signal obtained by an image pickup element and controls a focus (focus lens) to maximize the contrast.
Additionally, a phenomenon called a pumping is conventionally known in which, when a focus is moved, an angle of view (focal length) is varied as though zooming is performed even though a zoom is fixed in a taking lens. To prevent such a pumping phenomenon, there is a known lens controller having a view angle correction (pumping correction) function which moves a zoom by a motor to prevent a view angle variation when a focus is moved (for example, see Japanese Patent Application Laid-Open No. 2001-42199).